Forward osmosis (FO) process makes use of the natural osmosis phenomenon for the transport of water from a low solute concentration feed solution to a high solute concentration draw solution across a semipermeable membrane, with the osmotic pressure difference between the feed and the draw solution acting as the driving force. After the water naturally permeates into the draw solution without external energy input, the diluted draw solution can then be recycled for reuse in the FO process while high quality water product can be produced.
The FO process has recently shown great potential for wastewater reuse and seawater desalination. It has various advantages over current membrane technology, especially the reverse osmosis (RO) process. These advantages include a lower energy consumption needed for the osmosis process and a lower fouling potential of the membrane. One of the most important challenges in utilizing the FO process for practical applications is the lack of such suitable membrane. Water permeate flux obtained with current FO membrane is usually lower than expected. The low permeate flux attributes to the severe internal concentration polarization (ICP) effect occurring in the porous support layer of the membrane.
Due to the limitations posed by the severe ICP effect on water permeate flux for current forward osmosis membranes, new forward osmosis membranes with superior water permeate flux and high solute rejection rate are desired.